The following invention relates to a method for the modification of a three-dimensional object displayed on a computer screen with the help of an input device.
Known graphics programs provide a multitude of possibilities to modify a displayed object. For example, it is possible to move the object to a different location, to rotate the object, or to compress or stretch the object in one or two dimensions.
High-end graphics programs, such as the AutoCAD(copyright) application software, are furthermore able to display several views of a given object simultaneously on the screen. These views usually include a three-dimensional view (e.g., isometric view). These graphics programs, however, allow modifications to the object only in the two-dimensional representations. When a change is performed in one two-dimensional view, the corresponding change is calculated for the other two-dimensional views. The user can thus view the effects of a modification that is performed simultaneously in all views, even in the three-dimensional view. These graphics programs, however, do not allow direct modifications to the object shown in the three-dimensional view.
It is the task of the present invention to provide a method for the direct modification of an object in the three-dimensional view with the help of an input device, preferably a mouse input device allowing only two-dimensional input.
This task is accomplished by a method comprising the following steps:
Creating a three-dimensional object; displaying a three-dimensional representation of the three-dimensional object on a computer screen; activating the three-dimensional object through an operation of the input device relating to the representation of the object; displaying a representation of a three-dimensional coordinate system on the computer screenxe2x80x94with the three-dimensional coordinate system being assigned to the active three-dimensional object; selecting one of the axes of the three-dimensional coordinate system assigned to the object by way of an operation of the input devicexe2x80x94with the input operation relating to the representation of the coordinate system displayed on the screen; shifting the origin of the coordinate system assigned to the object within a global three-dimensional coordinate system along a line defined by the orientation of the selected axis of the assigned coordinate system within the global three-dimensional coordinate system, and in a direction which is determined by an operation performed with the input device; computing the three-dimensional object relative to the global coordinate system after moving the object in accordance with the movement of the origin of the assigned coordinate system; and displaying a representation of the shifted three-dimensional object on the computer screen.
According to a preferred embodiment, the displayed object can also be rotated which is achieved by the following additional steps:
Selecting a first axis of the three-dimensional coordinate system assigned to the object through an operation of the input device with the input operation relating to the representation of the assigned coordinate system displayed on the screen; rotating the assigned coordinate system around either the second or third coordinate axisxe2x80x94with the second axis being selected, if a movement of the first axis towards the third axis is induced by means of the input device and whereby the rotation is performed around the third axis, if a movement of the first axis towards the second axis is induced by means of the input device; computing the three-dimensional object relative to the global coordinate system after rotation of the object in accordance with the rotation of the assigned coordinate system; and displaying a representation of the rotated three-dimensional object on the computer screen.
Preferably, the method according to the invention furthermore provides the ability to scale the three-dimensional object, which is achieved by the following steps:
Selecting an axis of the three-dimensional coordinate system assigned to the object through an operation of the input device with the input operation relating to the representation of the assigned coordinate system displayed on the screen; effectuating an extension or stretch operation to the selected axis of the coordinate system assigned to the object by means of the input device; computing the three-dimensional object relative to the global coordinate system after positive or negative stretch of the object along the selected axis of the assigned coordinate system; and displaying a three-dimensional representation of the stretched (or compressed) three-dimensional object on the computer screen.